GNU Linux-libre 4.9.337-gnu1
[releases.git] / drivers / tty / serial / digicolor-usart.c
1 /*
2  *  Driver for Conexant Digicolor serial ports (USART)
3  *
4  * Author: Baruch Siach <baruch@tkos.co.il>
5  *
6  * Copyright (C) 2014 Paradox Innovation Ltd.
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; either version 2 of the License, or
11  * (at your option) any later version.
12  */
13
14 #include <linux/module.h>
15 #include <linux/console.h>
16 #include <linux/serial_core.h>
17 #include <linux/serial.h>
18 #include <linux/clk.h>
19 #include <linux/io.h>
20 #include <linux/tty.h>
21 #include <linux/tty_flip.h>
22 #include <linux/of.h>
23 #include <linux/platform_device.h>
24 #include <linux/workqueue.h>
25
26 #define UA_ENABLE                       0x00
27 #define UA_ENABLE_ENABLE                BIT(0)
28
29 #define UA_CONTROL                      0x01
30 #define UA_CONTROL_RX_ENABLE            BIT(0)
31 #define UA_CONTROL_TX_ENABLE            BIT(1)
32 #define UA_CONTROL_SOFT_RESET           BIT(2)
33
34 #define UA_STATUS                       0x02
35 #define UA_STATUS_PARITY_ERR            BIT(0)
36 #define UA_STATUS_FRAME_ERR             BIT(1)
37 #define UA_STATUS_OVERRUN_ERR           BIT(2)
38 #define UA_STATUS_TX_READY              BIT(6)
39
40 #define UA_CONFIG                       0x03
41 #define UA_CONFIG_CHAR_LEN              BIT(0)
42 #define UA_CONFIG_STOP_BITS             BIT(1)
43 #define UA_CONFIG_PARITY                BIT(2)
44 #define UA_CONFIG_ODD_PARITY            BIT(4)
45
46 #define UA_EMI_REC                      0x04
47
48 #define UA_HBAUD_LO                     0x08
49 #define UA_HBAUD_HI                     0x09
50
51 #define UA_STATUS_FIFO                  0x0a
52 #define UA_STATUS_FIFO_RX_EMPTY         BIT(2)
53 #define UA_STATUS_FIFO_RX_INT_ALMOST    BIT(3)
54 #define UA_STATUS_FIFO_TX_FULL          BIT(4)
55 #define UA_STATUS_FIFO_TX_INT_ALMOST    BIT(7)
56
57 #define UA_CONFIG_FIFO                  0x0b
58 #define UA_CONFIG_FIFO_RX_THRESH        7
59 #define UA_CONFIG_FIFO_RX_FIFO_MODE     BIT(3)
60 #define UA_CONFIG_FIFO_TX_FIFO_MODE     BIT(7)
61
62 #define UA_INTFLAG_CLEAR                0x1c
63 #define UA_INTFLAG_SET                  0x1d
64 #define UA_INT_ENABLE                   0x1e
65 #define UA_INT_STATUS                   0x1f
66
67 #define UA_INT_TX                       BIT(0)
68 #define UA_INT_RX                       BIT(1)
69
70 #define DIGICOLOR_USART_NR              3
71
72 /*
73  * We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is
74  * only produced when the FIFO is filled more than a certain configurable
75  * threshold. Unfortunately, there is no way to set this threshold below half
76  * FIFO. This means that we must periodically poll the FIFO status register to
77  * see whether there are waiting Rx bytes.
78  */
79
80 struct digicolor_port {
81         struct uart_port port;
82         struct delayed_work rx_poll_work;
83 };
84
85 static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];
86
87 static bool digicolor_uart_tx_full(struct uart_port *port)
88 {
89         return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
90                   UA_STATUS_FIFO_TX_FULL);
91 }
92
93 static bool digicolor_uart_rx_empty(struct uart_port *port)
94 {
95         return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
96                   UA_STATUS_FIFO_RX_EMPTY);
97 }
98
99 static void digicolor_uart_stop_tx(struct uart_port *port)
100 {
101         u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
102
103         int_enable &= ~UA_INT_TX;
104         writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
105 }
106
107 static void digicolor_uart_start_tx(struct uart_port *port)
108 {
109         u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
110
111         int_enable |= UA_INT_TX;
112         writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
113 }
114
115 static void digicolor_uart_stop_rx(struct uart_port *port)
116 {
117         u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
118
119         int_enable &= ~UA_INT_RX;
120         writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
121 }
122
123 static void digicolor_rx_poll(struct work_struct *work)
124 {
125         struct digicolor_port *dp =
126                 container_of(to_delayed_work(work),
127                              struct digicolor_port, rx_poll_work);
128
129         if (!digicolor_uart_rx_empty(&dp->port))
130                 /* force RX interrupt */
131                 writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);
132
133         schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
134 }
135
136 static void digicolor_uart_rx(struct uart_port *port)
137 {
138         unsigned long flags;
139
140         spin_lock_irqsave(&port->lock, flags);
141
142         while (1) {
143                 u8 status, ch;
144                 unsigned int ch_flag;
145
146                 if (digicolor_uart_rx_empty(port))
147                         break;
148
149                 ch = readb_relaxed(port->membase + UA_EMI_REC);
150                 status = readb_relaxed(port->membase + UA_STATUS);
151
152                 port->icount.rx++;
153                 ch_flag = TTY_NORMAL;
154
155                 if (status) {
156                         if (status & UA_STATUS_PARITY_ERR)
157                                 port->icount.parity++;
158                         else if (status & UA_STATUS_FRAME_ERR)
159                                 port->icount.frame++;
160                         else if (status & UA_STATUS_OVERRUN_ERR)
161                                 port->icount.overrun++;
162
163                         status &= port->read_status_mask;
164
165                         if (status & UA_STATUS_PARITY_ERR)
166                                 ch_flag = TTY_PARITY;
167                         else if (status & UA_STATUS_FRAME_ERR)
168                                 ch_flag = TTY_FRAME;
169                         else if (status & UA_STATUS_OVERRUN_ERR)
170                                 ch_flag = TTY_OVERRUN;
171                 }
172
173                 if (status & port->ignore_status_mask)
174                         continue;
175
176                 uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
177                                  ch_flag);
178         }
179
180         spin_unlock_irqrestore(&port->lock, flags);
181
182         tty_flip_buffer_push(&port->state->port);
183 }
184
185 static void digicolor_uart_tx(struct uart_port *port)
186 {
187         struct circ_buf *xmit = &port->state->xmit;
188         unsigned long flags;
189
190         if (digicolor_uart_tx_full(port))
191                 return;
192
193         spin_lock_irqsave(&port->lock, flags);
194
195         if (port->x_char) {
196                 writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
197                 port->icount.tx++;
198                 port->x_char = 0;
199                 goto out;
200         }
201
202         if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
203                 digicolor_uart_stop_tx(port);
204                 goto out;
205         }
206
207         while (!uart_circ_empty(xmit)) {
208                 writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
209                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
210                 port->icount.tx++;
211
212                 if (digicolor_uart_tx_full(port))
213                         break;
214         }
215
216         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
217                 uart_write_wakeup(port);
218
219 out:
220         spin_unlock_irqrestore(&port->lock, flags);
221 }
222
223 static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
224 {
225         struct uart_port *port = dev_id;
226         u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);
227
228         writeb_relaxed(UA_INT_RX | UA_INT_TX,
229                        port->membase + UA_INTFLAG_CLEAR);
230
231         if (int_status & UA_INT_RX)
232                 digicolor_uart_rx(port);
233         if (int_status & UA_INT_TX)
234                 digicolor_uart_tx(port);
235
236         return IRQ_HANDLED;
237 }
238
239 static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
240 {
241         u8 status = readb_relaxed(port->membase + UA_STATUS);
242
243         return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
244 }
245
246 static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
247 {
248         return TIOCM_CTS;
249 }
250
251 static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
252 {
253 }
254
255 static void digicolor_uart_break_ctl(struct uart_port *port, int state)
256 {
257 }
258
259 static int digicolor_uart_startup(struct uart_port *port)
260 {
261         struct digicolor_port *dp =
262                 container_of(port, struct digicolor_port, port);
263
264         writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
265         writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
266         writeb_relaxed(0, port->membase + UA_CONTROL);
267
268         writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
269                        | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,
270                        port->membase + UA_CONFIG_FIFO);
271         writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
272                        port->membase + UA_STATUS_FIFO);
273         writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,
274                        port->membase + UA_CONTROL);
275         writeb_relaxed(UA_INT_TX | UA_INT_RX,
276                        port->membase + UA_INT_ENABLE);
277
278         schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
279
280         return 0;
281 }
282
283 static void digicolor_uart_shutdown(struct uart_port *port)
284 {
285         struct digicolor_port *dp =
286                 container_of(port, struct digicolor_port, port);
287
288         writeb_relaxed(0, port->membase + UA_ENABLE);
289         cancel_delayed_work_sync(&dp->rx_poll_work);
290 }
291
292 static void digicolor_uart_set_termios(struct uart_port *port,
293                                        struct ktermios *termios,
294                                        struct ktermios *old)
295 {
296         unsigned int baud, divisor;
297         u8 config = 0;
298         unsigned long flags;
299
300         /* Mask termios capabilities we don't support */
301         termios->c_cflag &= ~CMSPAR;
302         termios->c_iflag &= ~(BRKINT | IGNBRK);
303
304         /* Limit baud rates so that we don't need the fractional divider */
305         baud = uart_get_baud_rate(port, termios, old,
306                                   port->uartclk / (0x10000*16),
307                                   port->uartclk / 256);
308         divisor = uart_get_divisor(port, baud) - 1;
309
310         switch (termios->c_cflag & CSIZE) {
311         case CS7:
312                 break;
313         case CS8:
314         default:
315                 config |= UA_CONFIG_CHAR_LEN;
316                 termios->c_cflag &= ~CSIZE;
317                 termios->c_cflag |= CS8;
318                 break;
319         }
320
321         if (termios->c_cflag & CSTOPB)
322                 config |= UA_CONFIG_STOP_BITS;
323
324         if (termios->c_cflag & PARENB) {
325                 config |= UA_CONFIG_PARITY;
326                 if (termios->c_cflag & PARODD)
327                         config |= UA_CONFIG_ODD_PARITY;
328         }
329
330         /* Set read status mask */
331         port->read_status_mask = UA_STATUS_OVERRUN_ERR;
332         if (termios->c_iflag & INPCK)
333                 port->read_status_mask |= UA_STATUS_PARITY_ERR
334                         | UA_STATUS_FRAME_ERR;
335
336         /* Set status ignore mask */
337         port->ignore_status_mask = 0;
338         if (!(termios->c_cflag & CREAD))
339                 port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
340                         | UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;
341
342         spin_lock_irqsave(&port->lock, flags);
343
344         uart_update_timeout(port, termios->c_cflag, baud);
345
346         writeb_relaxed(config, port->membase + UA_CONFIG);
347         writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
348         writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);
349
350         spin_unlock_irqrestore(&port->lock, flags);
351 }
352
353 static const char *digicolor_uart_type(struct uart_port *port)
354 {
355         return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
356 }
357
358 static void digicolor_uart_config_port(struct uart_port *port, int flags)
359 {
360         if (flags & UART_CONFIG_TYPE)
361                 port->type = PORT_DIGICOLOR;
362 }
363
364 static void digicolor_uart_release_port(struct uart_port *port)
365 {
366 }
367
368 static int digicolor_uart_request_port(struct uart_port *port)
369 {
370         return 0;
371 }
372
373 static const struct uart_ops digicolor_uart_ops = {
374         .tx_empty       = digicolor_uart_tx_empty,
375         .set_mctrl      = digicolor_uart_set_mctrl,
376         .get_mctrl      = digicolor_uart_get_mctrl,
377         .stop_tx        = digicolor_uart_stop_tx,
378         .start_tx       = digicolor_uart_start_tx,
379         .stop_rx        = digicolor_uart_stop_rx,
380         .break_ctl      = digicolor_uart_break_ctl,
381         .startup        = digicolor_uart_startup,
382         .shutdown       = digicolor_uart_shutdown,
383         .set_termios    = digicolor_uart_set_termios,
384         .type           = digicolor_uart_type,
385         .config_port    = digicolor_uart_config_port,
386         .release_port   = digicolor_uart_release_port,
387         .request_port   = digicolor_uart_request_port,
388 };
389
390 static void digicolor_uart_console_putchar(struct uart_port *port, int ch)
391 {
392         while (digicolor_uart_tx_full(port))
393                 cpu_relax();
394
395         writeb_relaxed(ch, port->membase + UA_EMI_REC);
396 }
397
398 static void digicolor_uart_console_write(struct console *co, const char *c,
399                                          unsigned n)
400 {
401         struct uart_port *port = digicolor_ports[co->index];
402         u8 status;
403         unsigned long flags;
404         int locked = 1;
405
406         if (oops_in_progress)
407                 locked = spin_trylock_irqsave(&port->lock, flags);
408         else
409                 spin_lock_irqsave(&port->lock, flags);
410
411         uart_console_write(port, c, n, digicolor_uart_console_putchar);
412
413         if (locked)
414                 spin_unlock_irqrestore(&port->lock, flags);
415
416         /* Wait for transmitter to become empty */
417         do {
418                 status = readb_relaxed(port->membase + UA_STATUS);
419         } while ((status & UA_STATUS_TX_READY) == 0);
420 }
421
422 static int digicolor_uart_console_setup(struct console *co, char *options)
423 {
424         int baud = 115200, bits = 8, parity = 'n', flow = 'n';
425         struct uart_port *port;
426
427         if (co->index < 0 || co->index >= DIGICOLOR_USART_NR)
428                 return -EINVAL;
429
430         port = digicolor_ports[co->index];
431         if (!port)
432                 return -ENODEV;
433
434         if (options)
435                 uart_parse_options(options, &baud, &parity, &bits, &flow);
436
437         return uart_set_options(port, co, baud, parity, bits, flow);
438 }
439
440 static struct console digicolor_console = {
441         .name   = "ttyS",
442         .device = uart_console_device,
443         .write  = digicolor_uart_console_write,
444         .setup  = digicolor_uart_console_setup,
445         .flags  = CON_PRINTBUFFER,
446         .index  = -1,
447 };
448
449 static struct uart_driver digicolor_uart = {
450         .driver_name    = "digicolor-usart",
451         .dev_name       = "ttyS",
452         .nr             = DIGICOLOR_USART_NR,
453 };
454
455 static int digicolor_uart_probe(struct platform_device *pdev)
456 {
457         struct device_node *np = pdev->dev.of_node;
458         int irq, ret, index;
459         struct digicolor_port *dp;
460         struct resource *res;
461         struct clk *uart_clk;
462
463         if (!np) {
464                 dev_err(&pdev->dev, "Missing device tree node\n");
465                 return -ENXIO;
466         }
467
468         index = of_alias_get_id(np, "serial");
469         if (index < 0 || index >= DIGICOLOR_USART_NR)
470                 return -EINVAL;
471
472         dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
473         if (!dp)
474                 return -ENOMEM;
475
476         uart_clk = devm_clk_get(&pdev->dev, NULL);
477         if (IS_ERR(uart_clk))
478                 return PTR_ERR(uart_clk);
479
480         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
481         dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
482         if (IS_ERR(dp->port.membase))
483                 return PTR_ERR(dp->port.membase);
484         dp->port.mapbase = res->start;
485
486         irq = platform_get_irq(pdev, 0);
487         if (irq < 0)
488                 return irq;
489         dp->port.irq = irq;
490
491         dp->port.iotype = UPIO_MEM;
492         dp->port.uartclk = clk_get_rate(uart_clk);
493         dp->port.fifosize = 16;
494         dp->port.dev = &pdev->dev;
495         dp->port.ops = &digicolor_uart_ops;
496         dp->port.line = index;
497         dp->port.type = PORT_DIGICOLOR;
498         spin_lock_init(&dp->port.lock);
499
500         digicolor_ports[index] = &dp->port;
501         platform_set_drvdata(pdev, &dp->port);
502
503         INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);
504
505         ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
506                                dev_name(&pdev->dev), &dp->port);
507         if (ret)
508                 return ret;
509
510         return uart_add_one_port(&digicolor_uart, &dp->port);
511 }
512
513 static int digicolor_uart_remove(struct platform_device *pdev)
514 {
515         struct uart_port *port = platform_get_drvdata(pdev);
516
517         uart_remove_one_port(&digicolor_uart, port);
518
519         return 0;
520 }
521
522 static const struct of_device_id digicolor_uart_dt_ids[] = {
523         { .compatible = "cnxt,cx92755-usart", },
524         { }
525 };
526 MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);
527
528 static struct platform_driver digicolor_uart_platform = {
529         .driver = {
530                 .name           = "digicolor-usart",
531                 .of_match_table = of_match_ptr(digicolor_uart_dt_ids),
532         },
533         .probe  = digicolor_uart_probe,
534         .remove = digicolor_uart_remove,
535 };
536
537 static int __init digicolor_uart_init(void)
538 {
539         int ret;
540
541         if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
542                 digicolor_uart.cons = &digicolor_console;
543                 digicolor_console.data = &digicolor_uart;
544         }
545
546         ret = uart_register_driver(&digicolor_uart);
547         if (ret)
548                 return ret;
549
550         ret = platform_driver_register(&digicolor_uart_platform);
551         if (ret)
552                 uart_unregister_driver(&digicolor_uart);
553
554         return ret;
555 }
556 module_init(digicolor_uart_init);
557
558 static void __exit digicolor_uart_exit(void)
559 {
560         platform_driver_unregister(&digicolor_uart_platform);
561         uart_unregister_driver(&digicolor_uart);
562 }
563 module_exit(digicolor_uart_exit);
564
565 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
566 MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
567 MODULE_LICENSE("GPL");